article{ 
    padding: 30px;
    width: 400px;
    border: solid 3px #ddd;
}
div{ 
    width: 100px;
    height: 100px;
    margin-bottom: 10px;
    background-color: red;
}
div:nth-of-type(1){ 
    /*display: none;*/
    visibility: hidden; /*不会使隐藏元素的位置丢失*/
    /*opacity: 10%;*/
}
